Two-dimensional codistribution spectroscopy to determine the sequential order of distributed presence of species

•Two-dimensional (2D) codistribution spectroscopy for population dynamics of species.•Determination of the sequential order of distributed presence of species.•Different from the order of intensity variations analyzed by traditional 2D correlation.•Moment analysis for the center of gravity and spread of distributions along the perturbation axis.

Two-dimensional codistribution spectroscopy (2DCDS), a technique designed specifically for the analysis of population dynamics, such as temporal distributions of species during a chemical reaction, is described. 2D codistribution analysis focus on the signal features reflecting the distributed presence of species, instead of the variation patterns of perturbation-induced deviations from the reference state, which has been traditionally analyzed by two-dimensional correlation spectroscopy (2DCOS). This technique is derived from the moment analysis of spectral intensity distributions along the perturbation variable axis within a well-defined observation interval. Derivation and properties of 2D codistribution spectra are provided, and comparison is made to 2D correlation spectroscopy with the help of simulated IR spectra generated from model chemical reactions.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slide